An emotional Jimmy Kimmel revealed Monday that his son, Billy, had successful open-heart surgery shortly after his birth on April 21.

During the opening monologue for ABC's Jimmy Kimmel Live, the late-night host put comedy aside to talk, sometimes tearfully, about his son's health crisis, while expressing relief and thanks that his little boy is doing well.

He also delivered an impassioned speech urging governmental financial support for the National Institutes of Health, criticizing proposed budget cuts by President Trump and praising members of Congress who approved a package that adds to NIH funding.

Kimmel said his wife, Molly McNearney, had "an easy delivery, six pushes he was out" at Los Angeles's Cedars Sinai Hospital, but a nurse detected a heart murmur and some purple coloration in his skin. Testing revealed the heart problem, with more personnel and equipment arriving for further diagnosis.

"It's a terrifying thing," Kimmel said, choking back tears.

Billy, whose full name is William John Kimmel, underwent successful open-heart surgery early last week. "It was the longest three hours of my life," his father said.

Kimmel said his son will need two follow-up operations, one in a few months and then another when he's in his early teens.

Billy was able to come home six days after the operation, said Kimmel, who showed a picture of his son just after the operation, with various wires, tubes and medical equipment attached to him, and one of the smiling, device-free baby a few days later.

"He peed on his mother today while she was changing his diaper. He's doing all the things that he's supposed to do," Kimmel said.

Kimmel thanked doctors, nurses and other medical personnel by name, choking up at various points. His heartfelt emotion came through again as he expressed appreciation to family, friends and his wife, with his sense of humor shining through.

"We had atheists praying for us," he said, before referring to his fake feud with friend Matt Damon. "Even that son of a b---- Matt Damon sent flowers."

Kimmel, who doesn't usually get political or particularly partisan, then made an impassioned but composed plea on behalf of health-care funding, while praising people's ability, after Obamacare's passage, to get health insurance even if they have a pre-existing condition.

"President Trump last month proposed a $6 billion cut in funding to the National Institutes of Health and thank God our Congressmen made a deal last night to not go along with that. They actually increased funding by $2 billion and I applaud them," he said. "More than 40% of the people who would have been affected by those cuts to NIH are children and it would have had a major impact on a lot of great places, including Children's Hospital Los Angeles," where his son underwent surgery.

Medical coverage and treatment of children shouldn't be a partisan issue, he said.

"If your baby is going to die and it doesn't have to, it shouldn't matter how much money you make. I think that s something, whether you're a Republican or a Democrat or something else, we all agree on that," he said, as the audience applauded. "Whatever you believe, whoever you support, we need to make sure the people who are supposed to represent us understand this very clearly. Let's stop with the nonsense. This isn't football. There are no teams. We are the team. Don't let partisan squabbles divide us on something every decent person wants. We need to take care of each other."

The special heart-themed episode featured appearances by Dr. Mehmet Oz, who used a diagram to explain how the heart works, and Olympic gold medalist Shaun White, who was born with a heart condition similar to Billy's.

Kimmel is taking the rest of week off to be with his son and family, with guest hosts filling in for the first time on the show. Will Arnett will host Tuesday, with Anthony Anderson (Wednesday), Kristen Bell (Thursday) and David Spade (Friday) sitting in Kimmel's chair for the remainder of the week.